Pushbutton-controlled overload circuit breaker



Aug. 23, 1966 J. ELLENBERGER 3, 8,6 8

PUSHBUTTON-CONTROLLED OVERLOAD CIRCUIT BREAKER Filed Aug. 18, 1964 2Sheets-Sheet 1 27 26 Inventor. JHKOB ELLENBERGER by:

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Atiorney 5 Aug. 23, 1966 J. ELLENBERGER PUSHBUTTON-CONTROLLED OVERLOADCIRCUIT BREAKER Filed Aug. 18, 1964 2 Sheets-Sheet 2 4/ 77 w l V 7Inventor: JH/(OB E LLENBERGE R wwwf Mr/w Attorneys r: 3,268,688 PatentedAugust 23, 1966 20 Claims. (31. 200-116) The present invention relatesto a pushbutton-controlled overload circuit breaker which is providedwith thermally responsive as well as trip-free releasing means and witha contact bridge which is pivotable and slidable on a control rod whichis rigidly connected to the push button. When the circuit breaker isbeing switched off this contact bridge is pressed against an inclinedsurface and when the circuit breaker is being switched on, the contactbridge is taken along by the control rod by the engagement of a detentor projecting end on the contact bridge with a catch or shoulder on thecontrol rod until one end of the contact bridge engages behind a holdingdetent on the thermally responsive releasing means.

There is an overload circuit breaker of the above-mentioned type alreadyknown which may be employed in place of one of the conventional safetyfuses. This known circuit breaker may be produced in a simple manner andat a low cost and it operates reliably for a great length of time.However, this known overload circuit breaker has the disadvantage thatit cannot be released by hand and that its switch positions cannot beindicated by signal circuits.

It is an object of the present invention to improve this known overloadcircuit breaker in a manner so as to permit the same to be switched offby hand and to indicate its switch positions by means of signalcircuits. Another object of the invention is to design this overloadcircuit breaker so as to be of a simple construction, to be easilymanufactured, assembled and installed, and to take up very little space.

According to the invention, these objects are attained by providing thecontrol rod of the overload circuit breaker with a lever which has aninclined part on one end thereof and is pivotably mounted at its otherend on the control rod. When the pushbutton is pulled out of the housingof the circuit breaker the inclined part of the lever slides along anabutment or edge whereby the lever is pivoted toward and pressed againstthe thermally responsive releasing means which are thereby bent untilthe holding detent thereof disengages from and releases the contactbridge. V

The pushbutton may therefore be employed for switching on as well as forswitching off the circuit breaker according to the invention.Consequently, there is no need for a separate manual releasing element,and the size of the circuit breaker will therefore be reduced by thespace which is usually required by such an additional releasing element.

In order to maintain the lever in a position in which the inclined parton one end thereof engages with the mentioned abutment, the opposite endof the lever is connected to a leaf spring so that the adjacent fiatsurfaces of the lever and leaf spring normally lie flat on each other.The parallel outer edges of this leaf spring project laterally overthose of the lever and are slidable in longitudinal grooves in the twoopposite housing parts. The lever and the leaf spring are provided withcorresponding apertures by means of which they are loosely fitted over alateral projection on the free end of the control rod. The purpose ofemploying a leaf spring as a return spring for the lever is to save inspace. The lever and the leaf spring may be produced in a simple mannerby stamping operations in which a pair of small studs are also pressedout of the material of the lever which engage into correspondingapertures in the leaf spring and are riveted thereto. The lever and theleaf spring therefore form a single structural unit which during theassembly of the circuit breaker are simply fitted with theircorresponding apertures over the lateral projection on the free end ofthe control rod.

For preventing any interference in the movement of the lever and theleaf spring with the contact bridge when the latter is in the connectingor on position, the central parts of the free ends of the lever and leafspring are punched out so as to form a pair of arms on each of them. Theends of the two arms of the lever are bent at an inclined angle awayfrom the leaf spring and form the inclined part previously referred to.When the contact bridge is in the on position, these inclined arms ofthe lever engage upon an edge of the contact bridge which then forms thementioned abutment for the inclined part of the lever so that there isno need to provide any additional abutment. By the engagement of theinclined arms of the lever with the edge of the contact bridge theadvantage is also attained that the contact pressure is increasedbetween the contact bridge and the holding detent on the bimetal stripof the thermally responsive releasing means.

The end of the contact bridge which is most remote from the pushbuttonis bent over at an angle so as to project and form an abutment which, inthe off position of the circuit breaker, engages with a shoulder on thecontrol rod so that, when the pushbutton with the control rod thereon isthen depressed, this shoulder on the control rod acts upon the bent endof the contact bridge and takes the latter along until it engages behindthe holding detent on the bimetal strip.

In order to simplify the production of the housing of the circuitbreaker, this housing has an an inner recess into which a separateinsert is fitted which is provided with an aperture through which thecontol rod extends and with an inclined surface on which the contactbridge abuts when it is in the off position. This insert also serves asa bearing for guiding the control rod during its longitudinal movements.

An additional feature of the invention consists in providing on one-orboth sides of the contact bridge a slide bar which preferably consistsof insulating material and serves for the operation of signal contacts.Although both of these slide bars may either be employed for operatingopening or closing contacts, it is of particular advantage to design oneof these slide bars for the operation of opening contacts and the otherfor the operating of closing contacts. These slide bars may be guided ingrooves in the side walls of the housing of the circuit breaker. In thismanner the signal contacts will not be affected by jarring or vibrationssince they are always held in their particular position without springaction.

For actuating the slide bars, the contact bridge may be provided withlateral studlike projections on which the slide bars are mounted withconsiderable play in the direction of movement of the control rod. Thislarge play has the advantage that, when the circuit breaker is eitherswitched on or off, the contact bridge may move for a certain distancewithout moving the slide bars. The kinetic energy of the contact bridgewhichthen occurs produces a snap actuation of the signal contacts. Fromthe fact that the slide bars are located directly on the contact bridgethe advantage results that a perfect trip-free release is attained notonly of the main contacts but also of the signal contacts of the circuitbreaker.

In order to hold the slide bars safely on the studs of the contactbridge even in the off position of the contact bridge, the insert withthe inclined surface is provided with side walls which extend in thedirection of the control rod and cover the slide bars within the area inwhich they are mounted and secure them in their positions on the studsof the contact bridge. This also considerably facilitates the assemblyof the circuit breaker. The pushbutton together with the control rod andthe cont-act bridge together with the slide bars are first assembled soas to form a single structural unit which may subsequently be easilyinserted into the housing during the final assembly of the circuitbreaker. The side walls of the insert then hold the slide bars in theirproper position on the contact bridge.

The terminal strips carrying the signal contacts may be secured in asimple manner by being inserted into suitable recesses in the twohousing parts. They are then covered up by insulating plates so as to beinsulated relative to the main circuit. For securing these insulatingplates in their proper positions, an intermediate insulating member isplaced between them which, in turn, is secured to the housing by a rivetwhich secures the two housing parts to each other.

Another feature of the invention consists in the fact that the springwhich acts upon the contact bridge and serves for the trip-free releaseof the circuit breaker is supported on a fixed abutment which has anaperture through which the control rod extends and forms a separateelement which is inserted into suitable recesses in the walls of thehousing. This fixed abutment or insert insures that the cont-act bridgewill be switched at a uniform speed to the off position when operated byhand or when a short circuit occurs. This is an advantage over the knownoverload circuit breaker as previouslyy referred to which does not reactto a short circuit as quickly since by the pressure upon the pushbuttonthe force of the spring which is provided for the trip-free release isconsiderably reduced and this spring can therefore become active onlywith its residual spring pressure.

For the purpose of further simplifying the manufacture of the circuitbreaker according to the invention, the upper end of the control rod isprovided on opposite sides with recesses and this upper end is theninserted from one side into a corresponding recess in the lower end ofthe pushbutton. By fitting a sleeve tightly over the lower part of thepushbutton containing this recess, the pushbutton holds the upper end ofthe control rod securely with a viselike grip. According to a furtherfeature of the invention, this sleeve which locks the pushbutton to theend of the control rod is provided with an inner annular recess intowhich the release spring is inserted, the other end of which issupported on the mentioned insert. This insert therefore saves aseparate abutment for supporting the release spring.

The pushbutton and the locking sleeve are preferably made of differentcolors for the following purpose. When the circuit breaker according tothe invention is switched on, only the pushbutton of one particularcolor projects from the housing. If, however, the circuit breaker is inits off position, not only the pushbutton but also the differentlycolored locking sleeve is visible above the housing. The two differentswitch positions of the circuit breaker can therefore be easilyrecognized by the single color of the pushbutton or the two colors ofthe pushbutton and the locking sleeve.

In order to be able to adjust the bimetal strip as simply and accuratelyas possible and so as to require the smallest possible space for theseadjusting means one end of the bimetal strip is secured, preferably bywelding, to one arm of an angular metal strip which is inserted intocorresponding recesses in the two parts of the housing and the other armof which is provided with a setscrew which engages upon the bimetalstrip.

A further feature of the invention consists in the provision of verysimple and effective means for mounting the circuit breaker in a fixedposition on a control panel or the like. These means consist accordingto the invention of a small plate which is inserted between the twohousing parts at the end thereof adjacent to the pushbutton and isfurther secured by a rivet which connects the two housing par-ts to eachother. This small plate has a stud projecting from the housing at acertain distance from the threaded bushing on the end of the housing.When this threaded bushing is inserted into a bore in the control panelfrom the rear side thereof, this stud is also inserted into acorresponding recess or aperture in the panel adjacent to the mountingbore and it prevents the circuit breaker from turning when a lock nut isscrewed upon the bushing and tightened against the front side of thepanel.

The above-mentioned as well as numerous additional features andadvantages of the present invention will become more clearly apparentfrom the following detailed description thereof which is to be read withreference to the accompanying drawings, in which FIGURE 1 shows anelevation of an overload circuit breaker according to the inventionsubstantially in its natural size;

FIGURE 2 shows a view of the circuit breaker as seen from the left ofFIGURE 1;

FIGURE 3 shows a top view of FIGURE 1;

FIGURE 4 shows an enlarged elevation view, partly in section, of thecircuit breaker in the same position as shown in FIGURE 1 but withoutthe upper part of the housing;

FIGURE 5 shows a view of the inside of the housing P FIGURE 6 shows asimilar view of the other half of the housing which is omitted in FIGURE4;

FIGURE 7 shows the circuit breaker according to FIG- URE 4 in the OEposition;

FIGURE 8 shows the bimetallic strip with the fineadjustment deviceaccording to FIGURE 4;

*FIGURE 9 shows the upper part of the bimetallic strip, as seen in thedirection of the arrow IX in FIG- URE 8;

FIGURE 10 shows the upper part of the bimetallic strip, as seen in thedirection of the arrow X in FIG- UR-E 8;

FIGURE 11 shows a view of the lever and leaf spring unit as seen fromthe right of FIGURE 4;

FIGURE 12 shows a view of this unit, as seen from the left of FIGURE 11;while FIGURE 13 shows a view of the same unit as seen from the left ofFIGURE 12.

As illustrated in the drawings, the overload circuit breaker accordingto the invention comprises a housing which consists of two halves 1 and2 which are molded of plastic and are connected to each other by tubularrivets 3. A pushbutton 4 projects from the upper end of the housing '1,2, and is provided with a recess 5 in its lower end, as shown in FIGURE4, into which the similarly shaped upper end of a control rod 6 isinserted in a direction at right angles to the central axis of thepushbutton 4. The lower end of the pushbott-on 4 is enclosed by a sleeve7 which locks the upper end of the control rod 6 to the pushbutton 4.The lower part of sleeve 7 is provided with an inner annular recess 8into which a release spring 9 is inserted, the lower end of which issupported on an insert 10 of insulating material. The pushbutton 4 andthe locking sleeve 7 are differently colored-the pushbutton may, forexample, be black and the sleeve white-for indicating whether thecircuit breaker is in the on or off position. Thus, when the circuitbreaker is switched on, only the black button projects from the housing,while when the circuit breaker is switched off, the white sleeve 7 alsoprojects from the housing. The two housing parts 1 and 2 further enclosethe lower part of a threaded bushing .11 which has a square flange 12 onits lower end which is inserted into corresponding recesses 12 in thetwo housing parts 1 and 2 and is thus nonrotatably secured therein. The

insert is also held in a fixed position in suitable recesses 10 in thetwo housing parts 1 and 2.

The control rod 6 has a rectangular cross section and consists of solidinsulating material. For guiding this control rod 6, the upper wall ofthe insert 10 is provided with an aperture into which the control rod isinserted. On its lower end the control rod 6 is provided with a lateralprojection 13' which extends through corresponding openings in a lever14 and a leaf spring 15 which are riveted together at their lower ends,as shown particularly in FIGURES 11 to 13. Lever 14 is for this purposeprovided with a pair of studs 16 which are punched out of the materialof the lever and extend through corresponding apertures 15 in the leafspring 15 and are riveted to the latter. Along its lateral edges 17 and18, leaf spring 15 is guided in grooves 19 in both housing parts 1 and 2so as to be slidable in the longitudinal direction. The upper parts oflever 14 and leaf spring 15 are bifurcated by the provision of centralrecesses. The two arms 20 of lever 14 which are thus formed are bent attheir upper ends at 21 at an oblique angle away from the leaf spring 15.These bent ends 21 engage upon the edges 22 of the right end portions ofa contact bridge 23 which is pivotably and slidably mounted on thecontrol rod 6. In FIGURE 4, the contract bridge 23 is shown in itsconnecting or on position, whilein FIGURE 7 it is shown in itsdisconnecting or ofi position. In its on position according to FIGURE 4,the right end of the angular contact bridge 23, which is produced by astamping operation, is held in engagement with a holding detent 24 on abimetal strip 25.

This bimetal strip 25 is welded together with one arm 26 of an angularmetal strip 27 which is inserted into suitable slots in the two housingparts 1 and 2 and thus held in a fixed position. The other arm 28 ofstrip 27 carries a setscrew 29 which engages upon the bimetal strip 25.Thus, when the setscrew is screwed further into the arm 28, the bimetalstrip 25 is pivoted toward the right so that its holding detent 24 ismoved further away from the right end of the contact bridge 23. Thebimetal strip '25 carries a heating coil 30 which is insulated therefromand connected at one end to a terminal strip 31 which is provided with aconnecting screw 32.

As illustrated particularly in FIGURES 9 and 10, the upper end of thebimetal strip 25 has an aperture 33 into which a small copper plate isinserted which forms the holding detent 24. At one side of the bimetalstrip 25 this copper plate has a bore into which the upper end 30" ofthe heating coil 30 is inserted and riveted. At the other side of thebimetal strip 25, the copper plate 24 has lateral shoulders whichsupport it on the bimetal strip. In order to prevent the copper plate 33from being bent upwardly, a small bracket 34 is stamped out of thebimetal strip 25 and bent so as to abut with its lower edge 35 againstthe upper side of the copper plate 24, as shown particularly in FIGURE8.

The vertical arm 23' of contact bridge 23 cooperates with a fixedcontact 36 on a terminal strip 37 which is likewise provide with aconnecting screw 32. The main circuit therefore extends from theterminal strip 31 via the heating coil 30, the contact bridge 23, andthe contact 36 to the. terminal strip 37.

As shown particularly in FIGURE 7, the contact bridge 23 is acted uponby a spring 38 which serves for the trip-free release of the circuitbreaker and the lower end of which is supported on a stationary abutment39 which is inserted into suitable slots 39' in the two housing parts 1and 2. In order to prevent it from being bent, the angular part ofcontact bridge 23 is provided with a reinforcing corrugation 55 which isproduced by stamping.

Contact bridge 23 is provided on both sides with small studlikeprojections 40 which serve as means for connecting the contact bridge toa pair of slide bars 41 and 42. Both of these slide bars 41 and 42 areprovided at their upper ends with square holes 43 into which thestudlike projections 40 engage with considerable play which permits theslide bars to slide vertically on and relative to these projections 40.Slide bar 41 is adapted to act upon a contact spring 44 which cooperateswith another contact 45, while the slide bar 42 is adapted to act upon acontact spring 46 which cooperates with another contact 47. Thesecontacts 44 to 47 serve as signal contacts. They are covered up byinsulating plates 56 which are inserted into the two housing parts 1 and2 and are held in a fixed position by a spacing member 57 of insulatingmaterial which is likewise inserted between the two housing parts 1 and2. The insulating plates 56 and the spacing member 57 are provided withbores 58 which are in alignment with each other and are adapted toreceive a tubular rivet 3 for securing the two housing parts 1 and 2 toeach other after the various elements are installed therein. Theopposite sides of the spacing member 57 are provided with studlikeprojections which engage into apertures 59 in the insulating plates 56and prevent the spacing member 57 from turning. The ends of the signalcontacts 44 to 47 which project from the housing may be connected tosuitable signal circuits for indicating the particular switch positionin which the circuit breaker is set at any time. Slide bar 41 serves foropening the contacts 44 and 45, while slide bar 42 serves for closingthe contacts 46 and 47 when the contact bridge 23 is moved to its onposition as shown in FIGURE 4. Both contact springs 44 and 46 have thetendency to engage under initial tension against their associatedcontacts and 47.

For mounting the overload circuit breaker on a control I panel or thelike the threaded bushing 11 is provided with a buckled washer 48 and anut 49. In order to prevent the circuit breaker from turning when it isbeing mounted on this panel and when for this purpose the nut 49 isbeing tightened, a small metal plate 50 is inserted between the twohousing parts 1 and 2 and held in a fixed position therein by a tubularrivet 3 which passes through the housing parts and this metal plate.This metal plate 50 has a studlike projection 51 which engages from therear into a corresponding bore or recess in the control panel when thecircuit breaker is secured thereto.

When an excess current occurs, the bimetal strip 25 is heated by theheating oil 30 and bent so far in the clockwise direction from theposition as shown in FIGURE 4 that its holding detent 24 disengages fromthe contact bridge 23 and allows the latter, under the action of the release spring 9 to be pressed against the inclined surface 52 of theinsert 10, as illustrated in FIGURE 7. The lower, inwardly projectingend 53 of contact bridge 23 then engages with a shouder 54 on thecontrol rod 6 so that, when the circuit breaker is being switched on thecontrol rod 6 takes along the contact bridge 23 until its right end haspassed over and snapped behind the holding detent 24 on the bimetalstrip 25. When the operator of the circuit breaker then takes his fingeroh the pushbutton 4, the contact bridge 23 is suddenly pivoted by thespring 38 in the clockwise direction, whereby the vertical arm 23 of thecontact bridge is moved into engagement with the fixed contact 36 sothat the main circuit is closed. At the same time, the signal contacts44 to 47 are also actuated by the slide bars 41 and 42.

If the circuit breaker is to be switched off by hand, the pushbutton 4is pulled out of the housing 1, 2. The inclined ends 21 of the lever 14then slide along the edges 22 of contact bridge 23, whereby the lever 14is pivoted in the clockwise direction from the position as shown inFIGURE 4 and is thereby pressed against the bimetal strip 25 which isthen bent until its holding detent 24 is released from the end of thecontact bridge 23 permitting the latter under the action of the releasespring 9 to pivot to the off position, as shown in FIGURE 7, in whichthe contact bridge 23 engages upon the inclined surface 52 of the insert10. Simultaneously with the movement of the contact bridge 23 theconnecting bars 41 and 42 are also moved abruptly so that the signalcontacts 44 to 47 are likewise opened and closed instantaneously.

Although my invention has been illustrated and described with referenceto the preferred embodiment thereof, I wish to have it understood thatit is in no way limited to the details of such embodiment, but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed my invention, what I claim 1s:

1. A pushbutton-controlled overload circuit breaker having thermallyresponsive releasing means with a holding detent thereon, and trip-freereleasing means, a housing, a pushbutton guided in and projecting fromsaid housing, a control rod rigidly connected to said pushbutton, acontact bridge pivotable and slidable on said control rod within saidhousing, an inclined surface in said housing, said contact bridge beingpressed aganst said inclined surface when the circuit breaker isswitched off, said contact bridge having a projection and said controlrod having a shoulder associated with said projection, said contactbridge being taken along by said control rod when the circuit breaker isbeing switched on by the engagement of said projection with saidshoulder until one end of said contact bridge engages behind and isarrested by said holding detent of said thermally responsive releasingmeans, a lever having an inclined part at one end and pivotably mountedat the other end on said control rod, and means forming an edge in saidhousing associated with said lever so that, when said pushbutton ispulled out of said housing, said inclined part of said lever slidesalong said edge, whereby said lever is pivoted toward and pressedagainst said thermally responsive releasing means which are thereby bentuntil said holding detent thereof disengages from and releases saidcontact bridge.

2. An overload circuit breaker as defined in claim 1, further comprisinga leaf spring superimposed upon said lever and connected thereto at theend thereof opposite to said inclined end, said leaf spring havingparallel lateral edges projecting over said lever and slidably guided inlongitudinal grooves in two opposite walls of said housing, said controlrod having a lateral projections on the free end thereof, said lever andsaid leaf spring having corresponding apertures and loosely fitted bymeans of said aperture over said lateral projection on said control rod.

3. An overload circuit breaker as defined in claim 2, in which saidlever and said leaf spring are stamped parts, said lever havingpressed-out studs and said leaf spring having apertures corresponding tosaid studs, said studs engaging through said apertures in said leafspring and being riveted thereto.

4. An overload circuit breaker as defined in claim 3, in which the freeends of said lever and said leaf spring are bifurcated so that each ofthem has two arms, the two arms of said lever being bent at an obliqueangle away from said leaf spring to form said inclined part, andengaging upon an edge of said contact bridge when the latter is in theon position.

5. An overload circuit breaker as defined in claim 1, in which saidcontrol rod has a lateral projection on its free end forming saidshoulder, the end of said contact bridge most remote from saidpushbutton being bent over at an angle to form said first mentionedprojection and, in the off position of said contact bridge, engagingwith said projection on said control rod so as to be taken along by thelatter when said pushbutton is depressed.

6. An overload circuit breaker as defined in claim 1, further comprisinga separate insert member comprising said inclined surface, said insertmember having an aperture through which said control rod extends, saidhousing having an inner recess in at least one of its opposite wallsinto which said insert member is fitted so as to be rigidly securedthereto.

7. An overload circuit breaker as defined in claim 1,

8 further comprising signal contacts, and a slide'bar pref er-ablyconsisting of insulating material on at least one side of and connectedto said contact bridge for actuating said signal contacts.

8. An overload circuit breaker as defined in claim 1, further comprisingopening and closing signal contacts, and slide bars on opposite sides ofand connected .to said contact bridge, one of said slide bars adapted toactuate said opening contacts and the other slide bar adapted to actuatesaid closingcontacts.

9. An overload circuit breaker as defined in claim 8, in which the innersides of the side walls of said housing have grooves, said slide barsbeing guided in said grooves.

10. An overload circuit breaker as defined in claim 7, in which saidcontact bridge has a stud on at least one side thereof, said slide barhaving an aperture therein, said stud engaging into said aperture withconsiderable play in the direction of movement of said control rod.

11. An overload circuit breaker as defined in claim 10, furthercomprising a separate insert member comprising said inclined surface andhaving an aperture through which said control rod extends, and means forholding said slide bar on said stud of said contact bridge when saidcontact bridge is in the ofi. position.

12. An overload circiut breaker as defined in claim 11, in which saidmeans comprise a side wall of said insert member extending in thedirection of said control rod and covering said aperture of said slidebar when said contact bridge is in the otf position.

13. An overload circuit breaker as defined in claim 7, furthercomprising supports carrying said signal contacts and secured inrecesses provided in at least one wall of said housing, and at least oneinsulating plate covering said supports.

14. An overload circuit breaker as defined in claim 8, in which saidhousing consists of two separate parts, and further comprising supportscarrying said signal contacts and secured in recesses provided in theopposite walls of said two housing parts, insulating plates coveringsaid supports, an insulating member inserted between said insulatingplates for maintaining the latter in a fixed position in said housing,said insulating member having an aperture, and a rivet extending throughsaid aperture in said insulating member and through correspondingapertures in said two housing parts for securing said insulating memberand said two housing parts to each other.

15. An overload circuit breaker as defined in claim 1, furthercomprising a fixed abutment member mounted in recesses in the oppositewalls of said housing and having an aperture, said control rod extendingthrough said aperture, said trip-free releasing means comprising a coilspring on said control rod and having one end acting upon said contactbridge and the other end supported on said fixed abutment member.

16. An overload circuit breaker as defined in claim 1, in which the endof said control rod which is connected to said pushbutton is provided onopposite sides with recesses, the lower part of said pushbutton having arecess of a shape corresponding to that of said recessed end of saidcontrol rod, said end of said control rod being inserted into saidrecess in said pushbutton in a direction at right angles to the centralaxis of said pushbutton, and a sleeve fitted over and enclosing thelower part of said pushbutton and locking said end of said control rodand said pushbutton to each other.

17. An overload circuit breaker as defined in claim 16, in which saidlocking sleeve has an inner annular recess, and a release springinserted into and acting with one end upon the bottom of said annularrecess and thus upon said pushbutton, the other end of said releasespring being supported on said insert.

18. An overload circuit breaker as defined in claim 16, in which saidpushbutton and said locking sleeve are differently colored.

19. An overload circuit breaker as defined in claim 1,

in which said thermally responsive releasing means comprise a bimetalstrip, said holding detent being secured to said bimetal strip near oneend thereof, an angular metal strip mounted in corresponding recesses inthe opposite walls of said housing and having one arm rigidly secured tothe other end of said bimetal strip and supporting said bimetal strip,and a setscrew screwed into the other arm of said angular strip andadapted to engage upon said bimetal strip for adjusting the same.

20. An overload circuit breaker as defined in claim 1, in which saidhousing consists of two separate parts having corresponding apertures,and further comprising a small plate having an aperture inserted betweensaid two housing parts at the end thereof adjacent to said push- 10 saidplate and said housing parts for securing said plate and said housingparts to each other, said plate having a stud projecting from saidhousing at a certain distance from said pushbutton, said stud beingadapted to engage into a control panel or the like so as to prevent saidcircuit breaker from turning when mounted on said panel.

References Cited by the Examiner UNITED. STATES PATENTS 10 2,816,19212/1957 Ingwersen 200116 2,895,028 7/ 1959 Ellenberger 20088 2,952,7579/1960 Ellenberger 2001 16 3,031,542 4/ 1962 Ellenberger 2001 16 button,and a rivet extending through said apertures in 15 BERNARD A. GILHEANY,Primary Examiner.

1. A PUSHBUTTON-CONTROLLED OVERLOAD CIRCUIT BREAKER HAVING THERMALLY RESPONSIVE RELEASING MEANS WITH A HOLDING DETENT THEREON, A TRIP-FREE RELEASING MEANS, A HOUSING, A PUSHBUTTON GUIDED IN AND PROJECTING FROM SAID HOUSING, A CONTROL ROD RIGIDLY CONNECTED TO SAID PUSHBUTTON, A CONTACT BRIDGE PIVOTABLE AND SLIDABLE ON SAID CONTROL ROD WITHIN SAID HOUSING, AN INCLINED SURFACE IN SAID HOUSING, SAID CONTACT BRIDGE BEING PRESSED AGAINST SAID INCLINED SURFACE WHEN THE CIRCUIT BREAKER IS SWITCHED OFF, SAID CONTACT BRIDGE HAVING A PROJECTION AND SAID CONTROL ROD HAVING A SHOULDER ASSOCIATED WITH SAID PROJECTION, SAID CONTACT BRIDGE BEING TAKEN ALONG BY SAID CONTROL ROD WHEN THE CIRCUIT BREAKER IS BEING SWITCHED ON BY THE ENGAGEMENT OF SAID PROJECTION WITH SAID SHOULDER UNTIL ONE END OF SAID CONTACT BRIDGE ENGAGES BEHIND AND IS ARRESTED BY SAID HOLDING DETENT OF SAID THERMALLY RESPONSIVE RELEASING MEANS, A LEVER HAVING AN INCLINED PART AT ONE END AND PIVOTABLY MOUNTED AT THE OTHER END ON SAID CONTROL ROD, AND MEANS FORMING AN EDGE IN SAID HOUSING ASSOCIATED WITH SAID LEVER SO THAT, WHEN SAID PUSHBUTTON IS PULLED OUT OF SAID HOUSING, SAID INCLINED PART OF SAID LEVER SLIDES ALONG SAID EDGE, WHEREBY SAID LEVER IS PIVOTED TOWARD AND PRESSED AGAINST SAID THERMALLY RESPONSIVE RELEASING MEANS WHICH ARE THEREBY BENT UNTIL SAID HOLDING DETENT THEREOF DISENGAGES FROM AND RELEASES SAID CONTACT BRIDGE. 